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The present invention relates to a method for detecting microorganisms such as mold.
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Sugars in the form of independent bodies (free) or glycoconjugates (glycoproteins and glycolipids) are important biological molecules in various technology fields. Accordingly, it is an important problem in the technology fields to detect the presence and absence of sugars. Glucose sensors now routinely used to detect the presence and absence of sugars are based on electrochemical methods of detecting the glucose oxidized by enzyme and the redox active species produced in this process.
The biosensor field has been significantly developed by methods of using non-physiological electron acceptors and methods of using the direct electron transfer conducted between the active site of enzyme and the electrode. Nevertheless, in general, the low stability of enzymes and the sensitive change in activity of the enzyme associated with various factors which cannot be controlled are known as the limitations of the biosensor. For this reason, in the current research areas, sugar sensors which do not use an enzyme have been very actively developed.
Among them, one approach is a method based on the direct electrocatalytic oxidation of glucose. This method has been developed by using metal nanoparticles as a catalyst and using a carbon nanotube or graphene material as a catalyst support, but the systems reported to date still have a problem in that the activity of the catalyst is insufficient under the physiological environment.
Biosensors, which do not use an enzyme, use lectins that naturally make specific bondings with sugars in a natural way, and are configured in the form that concanavalin A is usually used. However, a more successful approach than the method is to introduce a boronic acid receptor capable of selectively binding a compound having a 1,2 or 1,3-diol functional group, and the compound having a 1,2 or 1,3-diol functional group is a common constituent element of sugars. The advantages of using a synthetic receptor are low costs, high stability, and the ability to relatively easily change the structure in order to apply the synthetic receptor to optimal sensing properties. In order to apply these results to a biosensor, a reaction of forming esters needs to be accompanied simultaneously by a signaling process which causes a change in optical (absorption, fluorescence, or holographic) or electrical properties.
There are prior art documents that configure an optical sensor based on the aforementioned approach.
Methods tried in U.S. Pat. Nos. 6,011,984 and 5,512,246 are methods of detecting glucose by using dyes attached to boronic acid groups and using a fluorescence method. The patents use the fact that when a boronic acid including a functional dye binds to sugar, the dye is affected by characteristics. Electrochemical sensors are actuated by an aqueous electroactive compound or a film fixed on the surface of an electrode.
The sensors of the first type disclosed in U.S. Pat. No. 6,011,984 most frequently used ferrocenyl boronic acid, and the ferrocenyl boronic acid generates a change in oxidation reduction potential caused by a complexation reaction in the presence of hydroxyl groups. In addition, the sensors of the second type disclosed in U.S. Pat. No. 5,512,246 used a conductive polymer modified with a boronic acid functional group. The sensors of the second type were carried out by a method of forming a boronic acid single layer on a gold electrode, or a method of forming a polymer layer including a boronic acid functional group on an electrode.
The approach to an electrochemical glucose sensor is reported in U.S. Pat. No. 6,797,152, and the patent used a method of binding an aniline boronic acid polymer to glucose, and generating signals depending on the concentration of glucose. The signal to be analyzed changes an open-circuit potential. The patent failed to suggest an experimental evidence in spite of the conductivity mentioned in the claim. Furthermore, the concentrations of glucose and fructose, which can be maximally detected, were about 40 mM.
When all the prior art sensors previously mentioned are reviewed, the sensors were described from one or more different viewpoints in terms of electrical polymerization conditions of an aniline boronic acid polymer, the form of analytical signal, a detectable concentration range, and the like.
DISCLOSURE OF THE INVENTION
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Therefore, an object of the present invention is to provide a method for detecting an analyte commonly having a cis-diol group, such as sugars, hydroxylic acids, polyhydroxyl acids, and polyhydroxyl aldehydes, and an electrode capable of detecting an analyte having a cis-diol group.
Another object of the present invention is to provide a method capable of identifying the presence and absence of an analyte by the five senses via detection of the electrical signals.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for detecting an analyte according to an example of the present invention including: coating an electrode with at least one of an aniline polymer, a thiophene polymer, a pyrrole polymer, carbon nanotube, and graphene, which are formed by substituting hydrogen of each monomer with boronic acid and subjecting the resulting monomer to electropolymerization; exposing the electrode to an analyte present in a solution or in the air; and measuring an impedance generated from the electrode exposed to the analyte.
According to an example related to the present invention, the coating of the electrode includes: reacting at least one of an aniline monomer, a thiophene monomer, a pyrrole monomer, a monomer of carbon nanotube, and a monomer of graphene with phenyl boronic acid to substitute hydrogen of the monomer with boronic acid; subjecting the monomer in which hydrogen is substituted with boronic acid to electropolymerization at a predetermined acid concentration and under a predetermined anodic switching potential condition; and coating the electrode with the polymer formed by electropolymerization.
According to another example related to the present invention, it is possible to determine the presence and absence of the analyte from a change in conductivity.
According to still another example related to the present invention, the analyte may include at least one of glucose, fructose, lactic acid, galactose, sialic acid, and microorganisms.
According to yet another example related to the present invention, the aniline polymer includes a 3-aminophenylboronic acid polymer formed by substituting hydrogen of an aniline monomer with boronic acid and subjecting the resulting monomer to electropolymerization, and the a 3-aminophenylboronic acid polymer may be formed by subjecting a 3-aminophenylboronic acid monomer to electropolymerization under conditions of maintaining a sulfuric acid (H2SCO4) concentration of 0.2 M or less and an anodic switching potential of 0.9 V or less compared to an Ag/AgCl reference electrode.
Further, the present invention discloses an electrode including a cis-diol group receptor in order to realize the aforementioned problem. In an electrode provided in a sensor which detects an analyte having a cis-diol group by measuring an impedance, the electrode includes a cis-diol group receptor, and the cis-diol group receptor is formed by being coated with at least one of an aniline polymer, a thiophene polymer, a pyrrole polymer, carbon nanotube, and graphene, which are formed by substituting hydrogen of each monomer with boronic acid and subjecting the resulting monomer to electropolymerization.
According to an example related to the present invention, the cis-diol group receptor may be configured so as to be reacted with a sugar having a cis-diol group in a carbon ring or bacteria.
According to the present invention as described above, it is possible to provide an electrochemical detection method of a material including sugar and cis-diol such as hydroxyl acid. The present invention uses a product obtained by coating an electrode with an aniline polymer formed by substituting hydrogen of an aniline monomer with boronic acid and subjecting the resulting monomer to electropolymerization as a biosensor, and the present invention may determine the presence and absence of an analyte by measuring the impedance.
In addition, the present invention may provide a user with information on the presence and absence of an analyte by transmitting a result of a change in conductivity shown as a result of detection to the user.
BRIEF DESCRIPTION OF THE DRAWINGS
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FIG. 1 is a molecular structure illustrating an example of an analyte to be detected by using a method for detecting the analyte proposed by the present invention;
FIG. 2 is a flowchart of the method for detecting the analyte related to an example of the present invention;
FIGS. 3a and 3b are a molecular structure of an aniline monomer and an aniline polymer, respectively;
FIG. 4 is a molecular structure of phenyl boronic acid;
FIGS. 5a and 5b are a molecular structure of an aniline monomer in which hydrogen is substituted with boronic acid and an aniline polymer, respectively;
FIG. 6 is a graph for describing a condition of forming an aniline polymer by subjecting an aniline monomer in which hydrogen is substituted with boronic acid to electropolymerization;
FIG. 7 is a graph of the results of experiments for demonstrating the accuracy and effectiveness of the analyte detection method of the present invention;
FIG. 8 is an equivalent circuit used in the experiment of FIG. 7;
FIG. 9 is a graph illustrating the results of the detection of glucose by using the method for detecting an analyte according to the present invention at each concentration;
FIG. 10 is a graph illustrating the results of the detection of fructose by using the method for detecting an analyte according to the present invention at each concentration;